Bitcoin Core v30 Sparks Debate Over Data Limit Increase

At the heart of the Bitcoin Core v30 controversy lies a technical feature called OP_RETURN, which enables users to attach extra data to transactions without affecting spendable coins. The upcoming update proposes raising the limit for this data-carrying capability, allowing for larger messages, proofs, or files to be embedded directly into the Bitcoin blockchain. Supporters argue this provides a cleaner, safer method for data attachment since OP_RETURN outputs remain provably unspendable, preventing the system from becoming clogged with unspendable transaction outputs.

The debate over OP_RETURN’s role in Bitcoin transactions dates back to at least 2010, according to BitcoinTalk forum discussions documented by BitMEX Research. This longstanding controversy reflects deeper questions about whether Bitcoin should primarily function as a medium of exchange or evolve into a more general data-storage network. The technical implementation may seem straightforward, but the philosophical implications have created one of Bitcoin’s most persistent ideological divides.

Leading Bitcoin figures have staked out opposing positions in the Core v30 debate. Luke Dashjr, lead maintainer of Bitcoin Knots—a fork of Bitcoin Core with stricter policy defaults—has consistently advocated for tighter relay rules, labeling non-financial data as ‘spam’ and pushing to filter what he considers misuse of block space. His position represents those who believe Bitcoin should remain focused on its original purpose as peer-to-peer electronic cash.

On the opposing side, Blockstream CEO Adam Back warns that introducing moderation or selective filtering sets a dangerous precedent that could leave Bitcoin vulnerable to censorship and threaten its long-term survival. This perspective emphasizes Bitcoin’s role as a censorship-resistant platform where no single entity can determine what constitutes valid usage. The pseudonymous developer Leonidas, creator of Bitcoin-native meme coin DOG, has accused Dashjr of attempting to ‘censor Ordinals and Runes transactions’ and manufacturing ‘a moral panic’ around child sexual abuse material on the blockchain.

The controversy intensified in May when allegations surfaced that the OP_RETURN limit increase was motivated by specific projects that would benefit from the changes, with leaked emails pointing to Jameson Lopp, chief security officer of Bitcoin custody firm Casa. Lopp denied these allegations the same month, but the incident highlighted how technical decisions in Bitcoin development often intersect with commercial interests and personal agendas.

Beyond the ideological conflict, Core v30 raises significant legal questions about liability for node operators. Andrew M. Bailey, professor of philosophy at the National University of Singapore and senior fellow at the Bitcoin Policy Institute, notes that while ‘bad transactions’ and ‘bad arbitrary data’ have existed on Bitcoin for over a decade, the legal protections remain unclear. ‘The most interesting legal issues the debate has produced are underdetermined by extant case or statutory law,’ Bailey told Decrypt, specifically questioning whether Section 230 protections would shield node operators from liability for hosting harmful data.

The technical implementation details create additional legal complexity. Bailey highlighted questions about whether there’s ‘a difference in legal liability for data stored in signatures or other witness items, addresses, multiple OP_RETURN outputs, or single OP_RETURN outputs.’ These distinctions could prove crucial in determining legal responsibility if harmful content becomes embedded in Bitcoin transactions through the expanded OP_RETURN capability.

Practically, however, Bailey suggested that relay policies implemented by node operators ‘will have next to no effect on which transactions are included in blocks, and which arbitrary data is smuggled within them.’ This underscores the limited power individual node operators have in controlling what data ultimately becomes part of Bitcoin’s immutable ledger.

Technical experts emphasize a crucial limitation in the current debate: once data exists on Bitcoin’s blockchain, it cannot be removed. Erin Redwing, CEO of Ordinals-based events firm Inscribing Atlantis, stated plainly: ‘The reality is that this data cannot be removed from Bitcoin, no matter what the anti-Core group says.’ She added that there’s no way ‘to filter data that already exists on Bitcoin’s blockchain’ and while ‘miners can choose what transactions to include in new blocks they mine, they cannot remove data that already exists on Bitcoin.’

This technical reality creates a fundamental constraint on what can actually be achieved through policy changes or filtering attempts. Lorenzo, core contributor to Fractal and founder of UniSat Wallet, acknowledged that ‘efforts to preserve and maintain Bitcoin’s immutable nature are entirely reasonable.’ He emphasized that ‘We see blockchains as reliable carriers of trust, built on cryptographic algorithms,’ adding that ‘It is precisely this trust in mathematics—rather than in human discretion—that has allowed such systems to develop long-term value.’

The Core v30 debate ultimately reflects Bitcoin’s ongoing identity crisis as it balances between being a pure monetary network and a broader data platform. As the October 2025 release approaches, the community must grapple with whether expanded data capabilities represent natural evolution or dangerous mission creep—a decision that will shape Bitcoin’s development for years to come while testing the limits of its decentralized governance model.